1. Field of the Invention
The present invention relates to a feeding device that conveys a sheet-like conveyance-target medium toward, for example, an image pickup unit provided to an image reading apparatus or an image forming unit provided to an image forming apparatus.
2. Description of the Related Art
A feeding device has been suggested that conveys a paper sheet, which is a sheet-like conveyance-target medium, toward, for example, an image pickup unit provided to an image reading apparatus or an image forming unit provided to an image forming apparatus.
In such a feeding device, among sheet-like conveyance-target media stacked on a tray, when a conveyed medium that becomes in contact with a pick roller in a rotating state is pressed onto a circumferential surface of the pick roller by a pressing unit, such as a separation roller, a conveyance force for sending the conveyed medium toward a conveyance destination, such as an imaging unit, is acted from the pick roller to the conveyed medium. With this, the conveyed medium is sent toward the imaging unit or the like. If a separation-target medium, which is placed on the conveyed medium but is not a conveyance target, is left, the pressing unit, such as a separation roller, makes contact with the separation-target medium to cause a separation force smaller than the conveyance force to be acted on this conveyed medium in a direction opposite to the conveyance force. With this, the separation-target medium is moved oppositely to the conveyed medium being sent by the pick roller in a sending direction. As a result of this opposite movement, when overlapping of the conveyed medium and the separation-target medium is eliminated, in other words, when the separation-target medium is separated from the conveyed medium, only the conveyed medium, that is, one conveyance-target medium, is conveyed to the conveyance destination, such as the imaging unit.
To improve the capability of separating the conveyed medium and the separation-target medium, a feeding device is suggested in which two separation rollers are disposed along a direction in which a pick roller rotates (for example, refer to Japanese Patent Application Laid-open Publication No. 2004-75242 and Japanese Patent Application Laid-open Publication No. 2004-123359). If the conveyed medium and the separation-target medium cannot be separated by one of the separation rollers on an upstream side along a rotating direction of a pick roller, a separation force is further acted by the other one of the separation rollers on a downstream side onto the conveyed medium and a conveyance-target medium, which is the separation-target medium, to separate the conveyed medium and the separation-target medium.
However, in the feeding device disclosed in Japanese Patent Application Laid-open Publication No. 2004-75242 or Japanese Patent Application Laid-open Publication No. 2004-123359, the separation-target medium overlapping the conveyed medium does not receive a pressing force onto the circumferential surface between the separation roller on the upstream side and the separation roller on the downstream side along the direction in which the pick roller rotates. Therefore, if the conveyed medium and the separation-target medium are not separated by the separation roller on the upstream side, when the separation-target medium is sent to the separation roller on the downstream side, the separation-target medium receives a separation force from the separation roller on the downstream side to be bent between the separation roller on the upstream side and the separation roller on the downstream side, thereby possibly causing a conveyance jam.